The M4000 stops the dangerous movement if at least one light beam is interrupted. As people inside the machine are not detected, a restart interlock is required on the punching machine. It must not be possible to reach the Reset control switch from the hazardous area.

In perimeter safeguarding, devices such as the SICK M4000 Multiple-Beam Perimeter Safety Guard are used to detect workers entering a specific area. Once through the perimeter, a person is no longer detected, but the machine will not restart when the safeguard is cleared. Manual resets are almost always used with perimeter safeguards. The reset button is placed well outside the area safeguarded and is used after all workers have exited the area within the perimeter safeguard. After reset, the manual restart of the machine can be initiated.

Perimeter safeguards are appropriate for applications where machines work without operator intervention. For machines where operator intervention is vital (e.g., replacing or moving parts), a light curtain might be a more appropriate safeguard.

Perimeter safeguarding uses lower resolution sensing, which can detect torsos as opposed to hands, fingers or arms. Given this, the Safety Distance (Dpf) increases. The optics of perimeter safeguards is specially designed for longer distances. As a general rule, perimeter safeguards are cost-effective.

The laser scanner can also be placed out of the way of work being done. The scanner can be positioned so that it will not be damaged or exposed to harm from corrosive substances, dropped parts and machinery. Common elements of industrial environments are not a danger to your device. With other forms of area safeguarding, replacement costs could be incurred quickly and repetitively.